Neutrophils obtained from the peripheral blood of patients with a serious bacterial infection and other inflammatory diseases have alteration in their morphology when the cells are stained with Wright stain. These include the presence of heavily stained granules (toxic granules), light blue inclusion bodies (Dohle bodies), and vacuolization of the cytoplasm. Investigations have indicated that toxic granules are azurophil granules which stain more heavily with Wright stain than granules in control neutrophils. The Dohle body is an inclusion of rough endoplasmic reticulum and the vacuoles noted within the cells probably are results of "lysosome lability" and can be characterized as phagolysosomes or autophagic vacuoles. The physiology of these cells is different from control cells in that they did not respond appropriately to chemotactic stimuli, and they do not clear bacteria in vitro as readily as do control neutrophils. Toxic neutrophils have increased oxygen utilization and produced an increase in the metabolism of glucose by the hexose monophosphate shunt during phagocytosis. They more avidly ingest viable bacteria and inert particles such as latex. That these preceding observations probably collectively represent changes in the membrane of toxic neutrophils has been substantiated by studies which indicate that toxic neutrophils more actively incorporate amino acids and 2-deoxyglucose into their cytoplasm. Further studies are underway which will more specifically characterize the alteration of the membranes of toxic neutrophils. BIBLIOGRAPHIC REFERNECES: DeChatelet, L.R., Mullikin, D., and McCall, C.E.: The generation of superoxide anion by various types of phagocytes. J. Infect. Dis. 131:443 (1975). DeChatelet, L.R., McPhail, L.C., Mullikin, D., and McCall, C.E.: An isotopic assay for NADPH oxidase activity and some characteristics of the enzyme from human polymorphonuclear leukocytes. J. Clin. Invest. 55:714 (1975).